Personality resemblance in adoptive families

Area of Science:

• Behavioral Genetics
• Psychology
• Human Development

Background:

• Twin studies are foundational for understanding genetic and environmental influences on personality.
• Adoption studies offer a complementary approach to validate twin-study findings.

Purpose of the Study:

• To examine genetic and environmental contributions to personality using adoption data.
• To assess personality resemblance among biologically and adoptively related family members.

Main Methods:

• Utilized the Texas Adoption Project data from 300 adoptive families.
• Administered personality assessments (MMPIs, 16PFs, Cattell scales) and parent ratings.
• Analyzed correlations, adjusted for rating bias, and employed multiple correlation techniques.

Main Results:

• Overall, low personality correlations (median < 0.10) were observed between related family members.
• Adjustments for rating bias and use of multiple correlations did not significantly increase predictive power.
• A subsample of well-measured children showed higher correlations, particularly for extraversion, suggesting heritability.

Conclusions:

• Adoption studies provide mixed support for strong genetic or environmental influences on overall personality resemblance within families.
• Evidence for heritability of personality traits, especially extraversion, is suggested in specific subsamples.
• Methodological considerations, like sample measurement quality, can impact the detection of genetic effects.